This invention relates to a field of optical apparatus and more particularly to apparatus for protecting an electro-optical detector used in a system for field diagnostic measurements of a continuous wave high energy laser beam.
Electro-optical detectors are generally operated in conjunction with primary optical systems for gathering and focusing the reflected radiation from a desired "target" or source, toward which the optical axis of the system is accordingly directed. In far field diagnostic measurements, a far field target is irradiated with a continuous high energy laser beam with a beam "on" time from 3-30 seconds. The intensity pattern in the far field is thereafter mapped using electro-optical detectors. However, the intensity of the target radiation is generally of a magnitude which, if unattenuated, can lead to detector failure or burnout.